1. Technical Field of the Invention
The present invention relates to an information network building method for building an information network in a house and to a network connection circuit used for connecting an information terminal to such an information network.
2. Description of the Related Art
In order to build an information network in a house, it has been necessary to lay down dedicated lines for information networks at the time of building the house or after the completion of the house. These dedicated lines ensure high-speed data transfer between terminals in the house, but unfortunately they are very costly.
Alternatively, radio transceivers may be connected to the terminals in the house to establish wireless communication. This approach provides a flexible layout of the terminals in the house. Wireless communication, however, may not be stable in a reinforced-concrete house, which readily attenuates electromagnetic waves.
Still another alternative solution may be to use a power line in the house for terminal-to-terminal communication. This approach also provides a flexible layout of the terminals in the house. The power line, however, carries a high voltage and requires a high-voltage proof combiner/distributor, which is difficult to design. Furthermore, noise generated by an apparatus connected to the power line being turned ON adversely affects communication signals, compromising high-speed data transfer.
In order to overcome these problems, Japanese Unexamined Patent Application Publication No. 2000-278551 (page 2, FIG. 1) described below discloses a communication control unit for home networking that ensures high-speed communication by using existing facilities. This home networking system utilizes a network of TV coaxial cables connected to a TV signal distributor which receives a TV signal sent from an antenna. Such a TV signal distributor is now provided in a typical regular house and group housing such as a condominium. A data signal is transferred from a communication terminal in one room to a communication terminal in another room via the TV coaxial cables. To achieve this, a transceiver that modulates the data signal into a transfer signal having a different frequency from the frequency band of the TV signal sent from the antenna is connected to a wall terminal for TV signal reception provided at the end of the TV coaxial cable in each room.
This communication control unit includes a frequency converter which is connected between the antenna and the TV signal distributor. This converter converts a transmission data signal sent from a TV coaxial cable via the TV signal distributor to a reception data signal having a frequency different from that of the transmission data signal and the frequency band of the TV signal, and then transmits the reception signal to other TV coaxial cables via the TV signal distributor.
Unfortunately, this home networking system requires labor and cost of connecting the communication control unit between the antenna and the TV signal distributor. Furthermore, it may degrade the TV signal quality.
Accordingly, an object of the present invention is to provide an information network building method for constructing an information network that ensures high-speed data transfer in a house while still saving labor and cost of introducing new facilities. Another object of the present invention is to provide a network connection circuit for connecting an information terminal to such an information network.